1. Field of the Invention
The present invention relates to a guard device for hypodermic needles and, more particularly, to guard devices for single and double ended needles.
2. Description of the Prior Art
A needle shield which must be removed from a needle hub before a syringe needle can be used for a medical procedure is described in each of U.S. Pat. Nos. 3,381,813, 3,934,722, 4,113,090 and 4,121,588. Each of these removable needle shields reveals several limitations, including: (1) after a liquid medicament has been drawn up in a syringe, medical personnel may occasionally delay the administration of the medicament, which delay requires retrieval and replacement of the needle shield to prevent contamination of the sterile needle and creates extra steps for busy medical personnel; (2) medical personnel often remove this needle shield by holding the needle shield between their teeth or lips. This practice has been associated with accidental self-puncture in the face or other bodily parts; (3) in order to re-cover a used needle with a previously removed needle shield, it is necessary to replace the needle shield back over the pointed end of the used needle, which replacement increases the risk to medical personnel of accidentally puncturing themselves with the pointed end of the used needle; and, (4) if the needle has been accidentally bent during a medical procedure or if the needle shield is replaced over the needle at an incorrect angle, the needle point may inadvertently pierce the side of the needle shield and puncture the fingers or hand.
Other U.S. Patents have issued which are directed to aspects of the present invention. U.S. Pat. No. 4,425,120 describes a needle guard for a removable needle which guard is attached to a syringe barrel. To remove the detachable needle from the syringe barrel, it is necessary to recover the used needle with a separate needle shield, which recovery increases the risk of puncture to medical personnel by the used needle point. In addition, the needle shield has an open end, which precludes sterility of the needle. U.S. Pat. No. 4,139,009 describes four longitudinal arms which are brought into lateral side-to-side contact with the intention of covering and protecting an enclosed needle. The front end of the cover and the lateral arms in side-to-side contact represent discontinuous locations which could permit microorganism penetration and contamination of the enclosed sterile needle. In addition, the arms in their normal unstressed condition are slightly bowed away from the longitudinal axis of the needle so that casual touching of the device could contaminate the needle through the interstices between the separated arms. When this device is pushed against a skin surface during the injection process, the arms must bow away from the longitudinal axis of the needle which bowing blocks visualization of the needle as it penetrates the skin and creates a hazard to the patient.
Various configurations of a double needle assembly are disclosed in U.S. Pat. Nos. 3,734,080 and 3,931,815, 2,460,641, 4,154,229, 4,295,476, 4,295,477, 4,312,362 and 4,340,068 for use in conjunction with evacuated blood collection systems and having removable needle shields.
With a double ended needle the risk of accidental contact with or puncture by either needle is substantially increased. In addition to the inherent danger from two potentially contaminated needles, other problems attendant a double needle blood collection system exist. For example, the needle engaging threads and lock (if used) of a normally reuseable container holder can become sufficiently worn to permit threaded disengagement during use. Such disengagement during the blood collection process exposes medical personnel to contact with or puncture by a potentially contaminated part of the posterior needle and the fluid being withdrawn. Withdrawal of blood in the blood collection process would also be interrupted. If the anterior needle is also inadvertently withdrawn, the potential for further exposure to contagious fluids exists.
After use, a single or a double ended needle assembly may contain, interiorly or exteriorly, a potentially infectious fluid which fluid may drip onto or otherwise come in contact with personnel, other equipment or a surface and pose a health hazard.